Problem: $ \left(\dfrac{4}{5}\right)^{-3}$
Solution: $= \left(\dfrac{5}{4}\right)^{3}$ $= \left(\dfrac{5}{4}\right)\cdot\left(\dfrac{5}{4}\right)\cdot \left(\dfrac{5}{4}\right)$ $= \dfrac{25}{16}\cdot\left(\dfrac{5}{4}\right)$ $= \dfrac{125}{64}$